(i) Over Production Living beings have an innate ability of producing own kind for the
continuity of race. It has been observed that more individuals of each kind are produced
than could possibly survive.

(ii) Struggle for Existence Individuals multiply in geometric ratio, whereas space and food
remain almost limited

(iii) Variations Members of a population vary is size, form and other characteristics even
though they look superficially similar, no two individuals are alike, These variations are
gradual and those with adaptive value are passed on to next generation.

(iv) Survival of the Fittest and Natural Selection During struggle for existence only those
individuals could survive which exhibit beneficial variations and adapt better to
changing environment. This is known as natural selection.

(v) Origin of Species Natural Selection results in modification of traits within a lineage,
which over a period of long time can bring about evolution of original species into new
one.